The present invention relates generally to an outboard motor including a water-cooled V-engine having cooling water jackets formed therein, and in particular to the engine designed such that cooling water such as sea water remaining in the cooling water jackets is readily discharged out of the outboard motor when the outboard motor is tilted up and pivoted either rightward or leftward.
Outboard motors having water-cooled engines are well known in the art and attached to sterns of boats. The outboard motors may be tilted up out of water for the purpose of maintenance. At this time, cooling water such as sea water remaining in cooling water jackets formed in the engines should be discharged out so as to prevent corrosion or rusting of the engines.
Japanese Utility Model Laid-Open Publication No. SHO 63-158530 discloses an outboard motor including an engine having cooling water jackets formed therein. When the outboard motor is tilted up and pivoted sideways, the cooling water jackets discharge out unwanted cooling water, which remains therein, through a discharge port formed at an underside of a lowermost cylinder of the engine.
Because the engine is an in-line engine having cylinders provided in vertical juxtaposition, the remaining cooling water can be discharged out of the outboard motor.
Engines for use in the outboard motors include a water-cooled V-engine having two sets or rows of vertically juxtaposed plural cylinders provided at right and left sides thereof. Each set of the cylinders is spaced a predetermined angle (a first angle) away from a central longitudinal axis of a boat. If the outboard motor employing such a V-engine is tilted up and pivoted rightward (or otherwise leftward) by a second angle, the set of the cylinders provided at the right side (or otherwise the left side) of the engine is spaced away from the axis of the boat by angles obtained by adding up the second angle to the first angle. As a result, cooling water within the cooling water jackets would not be satisfactorily discharged out of the discharge port formed in the lowermost cylinder.
An object of the present invention is to provide an outboard motor including a V-engine designed to smoothly discharge out cooling water remaining therein when the outboard motor is tilted up and pivoted sideways.
According to one aspect of the present invention, there is provided an outboard motor including a water-cooled V-engine, a horizontal shaft, and a vertical shaft, the outboard motor being tiltable up on the horizontal shaft and pivotable sideways on the vertical shaft. The water-cooled V-engine comprises right and left cylinder block portions each having plural cylinders formed therein, the cylinders being vertically juxtaposed, and cylinder heads disposed behind the right and left cylinder block portions, respectively. The plural cylinders of each of the right and left cylinder block portions have a cooling jacket formed therein, the cooling jacket allowing cooling water to flow therethrough to thereby cool the plural cylinders, and the right and left cylinder block portions have discharge portions formed at the lowermost cylinders thereof, the discharge portions each communicating with the cooling jacket of the plural cylinders of each of the right and left cylinder block portions, for discharging out cooling water remaining in the cooling jacket.
In the illustrated embodiment as described hereinafter, the lowermost cylinders have the discharge portions positioned at the same level as centers thereof. Therefore, when the outboard motor is tilted up and pivoted sideways for the purpose of maintenance, the cooling water remaining in the cooling jackets is smoothly discharged out through the discharge portions. It thus becomes possible to advantageously protect the engine of the outboard motor against corrosion or rusting.
By thus providing the cylinders with only the discharge portions, the drainage of the cooling water remaining in the cooling jackets can be achieved. The discharge portions may be piped.
In a preferred form of the present invention, the cooling jackets of the right and left cylinder block portions include inside bottom portions inclined forwardly of the outboard motor, the inside bottom portions each being contiguous with the discharge portions, such that the cooling water remaining in the cooling jackets is successively directed along the inside bottom portions into the discharge portions when the outboard motor is tilted up.
The inside bottom portions are continuous with the discharge portions. The inside bottom portions are inclined forwardly of the outboard motor. When the outboard motor is tilted up for the purpose of maintenance, the cooling water remaining within the cooling jackets is directed along the inside bottom portions into the discharge portions. The cooling water is then drained out of the discharge portions.
Preferably, the cooling water discharged from the discharge portions is discharged out of the outboard motor through a cooling water supplying pipe for supplying cooling water to the cooling jackets.